MXPA04000576A

MXPA04000576A - Energy-free refrigeration door and method for making the same.

Info

Publication number: MXPA04000576A
Application number: MXPA04000576A
Authority: MX
Inventors: R Cording Christopher
Original assignee: Afg Ind Inc
Priority date: 2001-07-19
Filing date: 2002-07-17
Publication date: 2005-02-17
Also published as: CA2454180A1; US20110089802A1; JP2014211302A; ES2338998T3; CN1556680B; JP2013064599A; EP1421321A4; US7891153B2; US20030062813A1; US20040222724A1; JP2008180502A; EP1421321A2; DE60234841D1; US20030197449A1; EP1421321B1; AU2002322509A1; ATE453092T1; CN1556680A; WO2003008877A3; PT1421321E

Abstract

A refrigeration door (10), and method for making the same, for controlling condensation, providing thermal insulation, with a desired amount of variable transmittance, without using electricity to heat the door (10). The energy-free refrigeration door includes a door frame housing (55) and an insulating glass unit comprising inner (70), middle (65), and outer (60) sheets of glass. A first sealant assembly (95) disposed around the periphery of the inner (70) and middle (65) sheets of glass forms a first chamber (94) between the inner (70) and middle (65) sheets of glass. A second sealant assembly (90) disposed around the periphery of the middle (65) and outer (60) sheets of glass forms a second chamber (92) between the middle (65) and outer (60) sheets of glass. A gas, such as krypton, air, or argon is held in the first (94) and second (92) chambers. The outer sheet of glass (60) and inner sheet of glass (70) each have an unexposed surface (62 and 72, respectively) that faces the middle sheet of glass (65). A low emissivity coating (73 and 63, respectively) is disposed on the unexposed surfaces (72 and 62) of the inner (70) and outer (60) sheets of glass so that the glass door (10) as a whole has a U value that prevents formation of condensation on the outer surface of the outer sheet (60) of the glass door, without the application of electricity to heat the door, while also providing the desired evaporation rate of condensation from the inner side of the inner sheet (70) of the glass door.

Description

DOOR FOR ENERGY-FREE REFRIGERATION AND METHOD FOR MAKING THE SAME PREVIOUS OF THE INVENTION 1. Field of the Invention The present invention relates, generally, with doors for cooling and, in particular, with a door for energy-free cooling that provides control of condensation, thermal insulation, and a desired amount of visible transmittance. More particularly, the cooling door of the present invention achieves these desired characteristics through the application of a low emissivity coating, without electrically heating the door. Throughout this application, the term "door for refligeration" is intended to refer to a door used for freezers, refrigerators and similar units and showcases. In addition, for purposes of this application, the term "energy-free" (as in door for energy-free cooling) means that no electricity is applied to the glass to heat the glass. 2. Discussion of the Background The doors for refrigeration for freezers, commercial refrigerators and the like, are typically constructed of glass, to allow the customer to see the products that are inside, for sale, without opening the door. However, when condensation forms on the glass (sometimes referred to as "fogging"), the customer is not able to see through the door to identify the products that are inside, which is undesirable from the point of view of the customer and also of the store owner or the retailer. Moisture condenses on the outside of the door for glass cooling, because the temperature of the outside surface of the glass is reduced below the ambient temperature in the store by the cooler cooled interior of the freezer or refigerator. When the temperature of the glass surface falls below the dew point of the air in the tent, moisture condenses on the surface of the glass. In addition, when a door is opened in a moist environment, the innermost glass sheet, which forms the inside of the door, is also momentarily exposed to the ambient air of the store and condensation may also form inside the door. Condensation inside the glass door also occurs because the temperature inside the glass door is below the dew point of the store's ambient air, to which it is exposed. As previously indicated, condensation on the glass door, which can frost, prevents the customer from seeing the products for sale through the glass door. Consequently, when the condensation or frost is on the glass door, the customer must perform the unpleasant task of opening the door for cooling, to identify the contents inside, which is not practical in a store with a large number of items. freezers or refrigerators. Opening each door for cooling is not only tedious and time consuming from the customer's perspective, it is also undesirable from the retailer's point of view, since it significantly increases the energy consumption of the retailer's freezers and refrigerators, resulting in , therefore, in higher energy costs for the retailer. There are several industrial performance standards that doors for refrigeration need to meet, in order to be acceptable. In the United States, many industries require freezer doors (but not refrigerator doors), which prevent external condensation when used in a medium with an outside temperature of 80 degrees Fahrenheit (26.6 ° C) , an external relative humidity of sixty percent (60%), and an internal temperature of minus forty degrees Fahrenheit (-40 ° F) (~ 40 ° C). Other countries have different requirements. As is well known in the art, a typical cooling door is comprised of an insulating glass unit (IGU), for its acronym in English), housed in a door frame. The IGU in a door for cooling is typically comprised of two or three sheets of glass sealed at its peripheral edges by a sealing assembly, generally referred to as an edge seal. In an IGU comprised of three sheets of glass, two insulating chambers are formed between the three sheets of glass. In an IGU comprised of two sheets of glass, a single insulating chamber is formed. Typically, the IGUs for refrigerators are constructed of two sheets of glass, while the IGUs for freezers employ three sheets of glass. Once sealed, the chambers are often filled with an inert gas, such as argon, krypton, or other suitable gas to improve the thermal performance of the IGU. More conventional methods for preventing or reducing condensation in a door for cooling involve supplying power to the door, including a conductive coating on one or more of the glass surfaces of the IGU, to electrically heat the glass.

The purpose of heating the glass is to maintain the temperature of the glass above the spray point of the hottest ambient air in the store. By heating the glass above the spray point, unwanted condensation and frost is prevented from forming on the glass in the door, providing a clear view into the interior of the cooling compartment. In a door consisting of a three glass IGU, an unexposed surface of one or two of the glass sheets is coated with a conductive material. The conductive coating is connected to a power supply by two conductor bars or other electrical connectors mounted on the opposite edges of the glass. As the current passes through the coating, the coating heats up, thereby heating the glass sheet to provide a condensation-free surface. The coating on the IGU of a door for cooling is normally applied to the unexposed surface of the outermost glass sheet. However, because condensation is sometimes formed inside the inner glass sheet, the unexposed surface of the innermost glass sheet can also be coated to heat to prevent condensation. There are numerous disadvantages and problems associated with these conventional heated cooling doors of the prior art. First, heating the door incurs an energy cost above and beyond the energy costs of the cooling system. In a standard-sized commercial freezer, the additional cost of heating a door to a freezer is substantial - based on the pricing of current electric service, such additional costs may be $ 100 per year or more for each freezer. Whereas many stores use multiple freezers, with some supermarkets and other food retailers using hundreds of freezers, the accumulated energy costs associated with such heated freezer doors are significant. Second, excess heat from conventional heated cooling doors will migrate to the refrigeration compartment, creating an additional load on the cooling systems, which results in even higher energy costs. Third, if the energy supplied to the door to heat it is too low, shut off or interrupted due to an interruption in power service, condensation and / or frost will form on the glass. If the dissipation of energy is too high, additional and unnecessary energy costs will be incurred. In order to reduce the occurrence of these problems, such heated glass doors often require precise control of the door heating system. In order to achieve the necessary precise control of the door heating system, an electrical control system is required, which results in increased design and manufacturing costs, as well as substantial operation and maintenance costs. Fourth, these electrically heated glass doors present a danger to the safety of customers, and a potential liability and exposure risk of retailers and refrigeration system manufacturers. The voltage applied to the glass door coating is typically 115 volts AC.

Shopping carts used by customers in stores are heavy and metal. If the shopping cart hits and breaks the glass door, electricity will be routed through the cart to the customer, which could cause serious injury or even death. U.S. Patents No. 5,852,284 and No. 6,148,563 describe applying a voltage to a coated glass with a conductive coating (which may be a low emissivity coating), to control the formation of condensation on the external surface of the door of glass. The conductive coating, such as a low emissivity coating, provides a resistance to electricity, which produces heat, while also providing desirable thermal characteristics. However, the doors for refrigeration described in these patents suffer from the disadvantages and problems previously described, associated with all electrically heated cooling doors. In addition to being used for conductivity, such low-emissivity coatings have been employed as other means to reduce condensation in doors for cooling. Specifically, a method for increasing the insulating value of the glass (the "R-value"), and reducing the heat loss from the cooling compartment, is to apply a low-emissivity (low E) coating to the glass. A low E coating is a microscopically thin, virtually invisible metal or metal oxide layer deposited on a glass surface to reduce emissivity, suppressing the flow of radiant heat through the glass.

Emissivity is the proportion of radiation emitted by a body or a black surface, and is the theoretical radiation predicted by Planck's law. The term emissivity is used to refer to the emissivity values measured in the infrared range, using the standards of the American Society for Testing and Materials (ASTM). Emissivity is measured using radiometric measurements and is reported as hemispheric emissivity and normal emissivity. The emissivity indicates the percentage of infrared radiation of long wavelength emitted by the coating. A lower emissivity indicates that less heat will be transmitted through the glass. Consequently, the emissivity of a glass sheet or an IGU has an impact on the insulation value of the glass or the IGU, as well as on the thermal conductivity (the "U-value") of the glass or the IGU. The U value of a glass sheet or an IGU is the inverse of its value R. In a multi-pane IGU, the emissivity of the IGU, which is the combined emissivity of the glass sheets that form the IGU, can be approximated by multiplying the emissivity of all the glass sheets together. For example, in a two-leaf IGU, with each glass sheet having an emissivity of 0.5, the total emissivity would be 0.5 multiplied by 0.5 or 0.25. Although low E coatings have been applied to the IGUs used in doors for cooling, with or without electrical door heating, such coatings and IGUs are not able to control the condensation or provide the thermal insulation required over the wide range of temperatures and environments in which such doors for refrigeration are used, without applying electricity to heat the doors. More specifically, despite the use of such a low E coating, doors for refrigeration that are not heated have failed to provide condensation control in applications in which the interior temperature of the refrigeration compartment is substantially close to or below freezing. Thus, in spite of the electrically heated and low-emissivity coated doors available, there is a need for a door for refligeration: (1) which provides the control of the necessary condensation and thermal insulation over a wide range of temperatures and environments; (2) with the desired amount of visible transmittance; (3) that avoids unnecessary energy costs and an undue burden on the cooling system, eliminating the need to supply electric power to heat the door; (4) that does not require a complex and expensive electrical control system, therefore, minimizing design, manufacturing, operation and maintenance costs; and (5) that it does not present a danger to the security of customers and a potential risk of liability and exposure to manufacturers and retailers.

SUMMARY OF THE INVENTION The primary object of the present invention is to overcome the deficiencies of the prior art, described above, by providing a door for energy-free cooling, with control of condensation, thermal insulation, and a desired amount of visible transmittance. Another key object of the present invention is to provide a door for cooling that does not use electrical energy, in order to reduce the condensation in the glass. Another key object of the present invention is to provide a door for cooling that controls condensation and that does not transfer significant heat to the interior of the freezer or refrigerator, additionally charging the cooling system and increasing energy costs. Still another object of the present invention is to provide a door for cooling with condensation control, which is easier and more economical to manufacture, operate and maintain than the doors and cooling systems of the prior art. Still another object of the present invention is to provide a door for cooling with condensation control, that is easier to design, operate and maintain. Another object of the present invention is to provide a method for making a door for cooling with condensation control, which does not use electricity to heat the glass to control condensation. Still another object of the present invention is to provide a door for refligeration with an emissivity of less than 0.04. Still another object of the present invention is to provide a door for refligeration with an emissivity of about 0.0025. Still another object of the present invention is to provide a door for cooling with a U-value of less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F). Still another object of the present invention is to provide a door for cooling with a U-value of about 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F). The present invention achieves these objects and others, by providing a door for energy free refligation, and a method for making the same, comprising a door frame housing an insulating glass unit, comprising inner, middle and inner glass sheets. external A first sealing assembly placed around the periphery of the inner and middle glass sheets forms a first chamber between the inner and middle glass sheets. A second seal assembly positioned around the periphery of the middle and outer glass sheets forms a second chamber between the middle and outer glass sheets. A gas, such as krypton, air or argon, is maintained in the first and second chambers. The outer glass sheet and the inner glass sheet each have an unexposed surface facing the middle glass sheet. A low-emissivity coating is placed on the unexposed surfaces of the inner and outer glass sheets, so that the glass door, as a whole, has a U-value that prevents the formation of condensation on the outer surface of the sheet external door glass, without the application of electricity to heat the door, while also providing the desired evaporation rate from the inner side of the inner leaf of the glass door. Additional features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present invention and, together with the description, serve additionally to explain the principles of the invention and to enable a person with experience in the pertinent technique, make and use the invention. In the drawings, similar reference numbers indicate identical elements or similar functionality. A more complete appreciation of the invention and many of the advantages that it entails, will be easily obtained as it is better understood, by reference to the following detailed description, when considered together with the accompanying drawings, wherein: FIGURE 1 describes a cooling system employing the present invention. FIGURE 2 discloses a door for cooling, in accordance with the present invention. FIGURE 3 is an illustration of a partial cross-sectional view of a door for cooling, in accordance with the present invention. FIGURE 4 is an illustration of a partial cross-sectional view of a door for cooling, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In the following description, for purposes of explanation and not limitation, specific details are exposed, such as particular coatings, coating processes, sheet thicknesses, sealant assemblies, number of sheets, separation of the sheets and methods for mounting the door, etc., in order to provide a complete understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention can be practiced in other embodiments that depart from these specific details. Detailed descriptions of well known coatings, coating processes, sealant assemblies, and door mounting methods are omitted so as not to obscure the description of the present invention. For purposes of this description of the invention, the terms such as external, internal, external and internal, are descriptions from the perspective of the interior of the freezer or refrigerator compartment, as is evident from the figures. Tests, as well as computer modeling, have shown that a U value (the conductivity of heat transfer through glass) of approximately 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F) is required to prevent condensation on the outside of the door glass for cooling, under the performance requirements for the US industry, as described above. As discussed, however, when the door is open, condensation may form on the inside of the inner glass sheet of the door, because the temperature of the inner surface of the sheet is below the dew point of the door. humid environmental air from the store to which it is exposed. Condensation, however, will dissipate once the door closes, since moisture evaporates in the freezer or refrigerator compartment. While condensation is present inside the door, the contents of the freezer or refrigerator are not visible through the door. Consequently, the evaporation rate, which determines the time lapse during which condensation is present, is an important design criterion. The more heat is transferred through the glass door to the inner surface of the glass door, the faster the condensation will evaporate inside the door. However, an increased heat transfer through the door results in increased energy costs of the cooling system. Consequently, the optimum U value of the glass door will depend on numerous factors, including the difference between the temperatures of the exterior and the interior, the thickness of the glass, the separation, the gas used in the IGU chambers, the number of sheets, the separating material, the ambient humidity, the coefficient of absorption of the coating in the far infrared spectrum, as well as the desired time for the evaporation of condensation. In addition, the costs associated with the selected components (ie, gas, seal assembly, glass, etc.), energy costs and other factors, are also design considerations. The preferred embodiment described below provides a U-value of 0.780 Kcal / hr-cm2oC (0.16 BTU / hr-sq ft F) which prevents condensation on the outside of the door, while allowing sufficient heat to penetrate through the door from the external environment to allow the condensation inside the door to evaporate in a reasonable amount of time. Some manufacturers of refrigeration systems require condensation to evaporate in a few minutes, and others require evaporation in one minute. The time required for the condensation to evaporate will vary according to the amount of time the door is open, the humidity in the store, the temperature of the cooling system compartment, the content of the cooling system, the heat transferred to the through the door (which depends on the value ü), and other factors. In the preferred embodiment of the present invention, as shown in Figure 1, a cooling system 5 includes a plurality of transparent reflectance doors 10, each having a handle 11. As will be described in more detail below, each door for cooling 10 includes an IGU 50, mounted on a frame 55. The interior of the cooling system includes a plurality of shelves 6 for holding the goods to be seen through the door. Referring to Figure 2, the cooling door 10 of the present embodiment is mounted to the opening of the cooling system with a hinge, which allows the door to open outwards. As discussed above, the cooling door 10 includes an IGU 50 housed in a frame 55. As shown in Figure 3, the IGU 50 is comprised of an outer glass sheet 60, an average glass sheet 65, and a inner glass sheet 70. The IGU 50 is housed in the frame 55 and also includes a first sealing assembly 90 that extends around the periphery of the inner surface 62 of the outer sheet 60, and the outer surface of the glass sheet means 65 for defining an external chamber 92 insulated, sealed substantially hermetically. Similarly, a second seal assembly 95 extends around the periphery of the outer surface 72 of the inner sheet 70 and the inner surface of the middle glass sheet 65 to define an insulated inner chamber 94, sealed in a substantially watertight manner. The outer surface 61 of the outer glass sheet 60 is positioned adjacent to the external environment 7. In other words, the outer surface 61 of the outer sheet 60 is exposed to the environment in which the refrigerator or freezer resides. . The inner surface 62 of the outer sheet 60 forms part of, and is exposed to, the outer chamber 92. In this preferred exemplary embodiment, the outer sheet 60 is 0.317 centimeters (one-eighth of an inch) thick, tempered, and the inner surface 62 of the outer sheet 60 is coated with a low emissivity coating 63. Specifically, in this embodiment, the low E coating is a low E coat coated by sputtering which includes ultra-hard titania as the base coat, to ensure a high level of thermal performance, and a high visible transmittance. This particular sputter-coated glass can be tempered after coating, and offers high transmission to visible light without high levels of color shading. The outer surface 61 of the outer sheet 60 is not coated. In this modality, the outer sheet 60 may, for example, be a Comfort Ti-PS glass sheet, 0.317 centimeter (one-eighth inch) thick, manufactured by AFG Industries, Inc. of Kingsport, Tennessee, which has a coating of low E that provides an emissivity of 0.05. As is well known in the art, the Comfort Ti-PS is cut to the appropriate size, tempered and bevelled before being integrated into the IGU 50. The middle glass sheet 65 is placed between the outer 60 and inner glass sheets 70. and is part of the outer chamber 92 and the inner chamber 94. The middle sheet 65 will separate 1.27 centimeters (one half inch) from the outer sheet 60 and the inner sheet 70, and is a tempered glass sheet, uncoated, of 0.317 centimeters (one eighth of an inch) thick. The inner glass sheet 70 is positioned adjacent to the interior of the freezer or refrigeration compartment 9, with its internal surface 71 exposed to the interior of the compartment 9. The outer surface 72 of the inner sheet 70 forms part of, and is exposed to the internal chamber 94. The outer surface 72 of the inner glass sheet 70 is also coated with a coating 73 of low emissivity. In this embodiment, the coating 73 on the outer surface 72 of the inner sheet 70 is the same as that described above with respect to the coating 63 of the inner surface 62 of the outer sheet 60. The inner surface 71 of the inner sheet 70 It is not coated. In this embodiment, the inner sheet 70 may also be, for example, a Comfort Ti-PS sheet, 0.317 centimeters (one-eighth inch) thick, manufactured by AFG Industries, Inc., which has the characteristics and coating described. In this exemplary embodiment, the chambers 92 and 94 are filled with air. In alternate modes, each chamber may be filled with a different gas, and the chambers may be filled with krypton, argon, or other suitable gas. The sheets 60, 65 are separated by a first sealing assembly 90, which extends around the periphery of the sheets 60, 65, keeping the glass sheet in a parallel, separate relationship, creating a chamber 92 between the sheets 60. , 65, while also sealing the chamber 92 of the external medium. In the same way, the sheets 65, 70 are kept separated by a second sealing assembly 95, which extends around the periphery of the sheets 65, 70, keeping the glass sheets in a separate, parallel relationship, creating the chamber 94 between the blades 65, 70, while also sealing the chamber 94 of the external medium. The sealing assemblies 90, 95 maintain a space of 1.27 centimeters (half an inch) between the outer sheet 60 and the middle sheet 65 and the inner sheet 70 and the middle sheet 65, respectively. Sealing assemblies 90, 95 of the present embodiment are preferably hot edge seals. "Warm edge" is used to describe an insulating glass sealant assembly that reduces heat loss better than combinations of conventional aluminum sealants and separators. Each of the sealing assemblies 90, 95 of this embodiment includes its own separator and desiccant, which replaces the need for a separate sealant, metal separator and desiccant, and has a heat transfer rate of 1,249 Kcal / hr-m- ° C (0.84 Btu / hr-ft-F) (sometimes referred to as the value). Mounts are sealants 90, 95 in this embodiment, are a composite extrusion containing a combination of a polyisobutylene sealant, a hot melt butyl sealant, a desiccant matrix, a rubber diaphragm and a vapor barrier. Suitable sealant assemblies of this type are manufactured and sold by TruSeal Technologies of Beachwood, Ohio, under the name "Comfort Seal". Referring to Figure 3, an IGU 50 is shown. The IGU 50 is comprised of glass sheets 60, 65 and 70, integrated by sealing assemblies 90 and 95. The IGU 50 is installed in a frame 55 in any suitable manner either known to those with experience in the art. The frame 55 is made of extruded plastic or other suitable well-known frame materials, such as extruded aluminum, fiberglass or other material. If, in another alternate embodiment, the frame 55 is formed of aluminum or other material, the door may require heating along its edges to ensure control of condensation around the edges of the door. Referring to Figure 1, a cooling system 5 is shown. The door frame 55 is coupled to the cooling compartment 8 in any suitable manner, as is well known in the art, such as by a long single-door hinge. , multiple hinges, or in a slot to slide the door to open and close it. In addition, the frame may include a door handle 11 or other suitable actuating means, as appropriate for the application. The cooling system 5, of which the door 10 forms a part, can be any system used to cool a compartment, such as that described in United States Patent No. 6,148,563, which is incorporated herein by reference. The above preferred embodiment provides a door for reflectance with a U value of 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F) (and an emissivity of 0.0025), which has been found to be suitable for applications of doors for freezers, which require the performance standards identified above, with respect to the industry of the United States. A U value of 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F), allows the door for cooling to easily meet the required performance standards, while also allowing enough heat to penetrate through the door from the external environment to evaporate the condensation formed inside the door in a reasonable period of time. In addition, the preferred embodiment provides a transmittance to visible light of sixty-six percent (66%). As an alternative to Comfort Ti-PS glass, another coated glass with low E can be used, such as, for example, Comfort Ti-R, Comfort Ti-AC, Comfort Ti-RTC and Comfort Ti-ACTC, all of which are available from AFG Industries, Inc., which, like the Comfort Ti-PS, are coated with low E based titanium / silver, manufactured by AFG Industries, Inc. Another type of suitable glass is the Comfort E2, which is coated with a pyrolytic process and is a glass coated with low E of tin oxide adulterated with fluorine, 0.317 centimeters (one eighth of an inch) thick, and which is manufactured by AFG Industries, Inc.

The Comfort E2, is suitable for some of the less stringent performance standards, due to its higher emissivity. The U value of the door for cooling 10 is determined by several design factors, including the number of sheets of glass, the thickness of the sheets, the emissivity of the IGU, the separation between the sheets, and the gas in the chamber . In the three-glass cooling door 10 of the preferred embodiment described above, the U-value of 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F) is achieved by using air as the gas that is maintained in the cameras, glass thicknesses of 0.317 centimeters (one eighth of an inch) in all the leaves, separation of 1.27 centimeters (half an inch), and an emissivity of the IGU of 0.0025. However, each of these factors can be varied resulting in numerous permutations of the values that could be combined to provide the same values of U. In addition, other applications may require a larger or smaller U-value, depending on the medium, the restrictions of costs and other requirements or considerations. Several computer simulations have been carried out to determine the U values of numerous IGUs for use in reflections 10 with a range of values of each of the various design parameters combined in different permutations. The following table includes the design parameters and corresponding calculated U values for various IGU configurations of three glasses. In addition to the design parameters listed in Table 1 below, all U-value calculations for the three-glass IGUs were calculated with each glass 0.317 centimeters (one-eighth of an inch) thick, and a total of two sides of the three glasses coated with low E. The tempering of the glass does not significantly affect the calculated performance values.

TABLE 1 Gas Separation in Type of Emissivity U Value between the IGU Coating (Kcal / hr-m2oC Sheets Cameras (Btu / hr-sq (centimeters ft-F)) (inches)) 1. 27 (1/2) air Ti-PS 0.0025 0.780 (0.16) 0. 793 (5/16) air i-PS 0.0025 1.073 (0.22) TABLE 1 (CONTINUED) In each of the tables included here, "Ti-PS", refers to the low E coating of a Comfort T-PS glass from AFG Industries and "CE2" refers to a low E coating of a Comfort E2 glass. AFG Industries, both described above. In addition, the U values in the tables are calculated as values in the "glass center", - because the computer simulation does not have the capacity to consider the sealant assembly. Consequently, there are no data or design criteria for the sealant assembly listed in the tables. In an alternate embodiment of two glasses of the present invention, shown in Figure 4, the IGU 50 includes an outer glass sheet 60 and an inner sheet 70, the frame 55, and a sealing assembly 90. In this two-glass embodiment , both the outer sheet 60 and the inner sheet 70 are 0.317 centimeters (one eighth of an inch) thick and include the same low E coating as described in the first embodiment, which is a low E silver coating with titania base. Again, both of the outer sheet 60 and the inner sheet 70 can, for example, be a Comfort Ti-PS glass sheet, 0.317 centimeters (one-eighth inch) thick, manufactured by AFG Industries, Inc. The coated sides of the sheets 60 and 70 are on the unexposed surfaces of the sheets, the sides 62 and 72, respectively, which are part of the chamber 92. Furthermore, the same sealing assembly 90 described above (the Comfort Seal), can be used and acts to provide a separation of 1.27 centimeters (half an inch) between the outer glass sheets 60 and internal glass sheets 70. Table 2 below includes the design parameters and corresponding calculated U values for several two glass IGUs. In addition to the design parameters listed in the following table, all calculations for two glasses were calculated with each glass being 0.317 centimeters (one eighth of an inch) thick, and a total of two sides of the two glasses being coated with low -AND. The tempering of the glass does not significantly affect the calculated performance values.

TABLE 2 Gas Separation in Type of Emissivity U Value between the IGU Coating (Kcal / hr-m2oC Sheets Cameras (Btu / hr-sq (centimeters ft-F)) (inches)) 1. 27 (1/2) air Ti-PS 0.0025 1.415 (0.29) 0. 793 (5/16) air Ti-PS 0.0025 1.756 (0.36) 1. 27 (1/2) argon Ti-PS 0.0025 1.122 (0.23) 0. 793 (5/16) argon Ti-PS 0.0025 1.366 (0.28) 1. 27 (1/2) krypton Ti-PS 0.0025 1.073 (0.22) 0. 793 (5/16) Krypton Ti-PS 0.0025 0.976 (0.20) TABLE 2 (CONTINUED) alternate modalities, any type of suitable coating processes can be employed, including pyrolytic (eg, as in Comfort E2), which is often referred to as chemical vapor deposition (CVD), spraying and coating by sputtering (for example, as in the Comfort Ti-PS). In addition, these processes can be applied using well-known online or offline manufacturing methods, as appropriate and appropriate for the quality and type of production and process. Likewise, any suitable low E coating may be employed, including a silver oxide-based tin oxide coating with titania base or fluorinated adulteration. Although the embodiments described above include low E coatings on the unexposed surfaces of two glass sheets, other embodiments of the present invention may include a low E coating applied to only one sheet of glass on either side or both sides. Similarly, in other embodiments, the average glass sheet (of a three-glass mode) may include a low E coating on either side (or both sides) instead of, or in addition to, sheet coatings of internal glass 70 and external 60. In yet another three-glass embodiment, the inner glass sheet 70 does not have a low E coating on either side of the glass sheet 70. Likewise, in an alternative to the embodiment of two sheets described above, the low E coating is present only on one sheet, or on both sides of both sheets. In general, the number of sheets that have the low E coating and the side (or sides) that have the coating, is a design choice. The total emissivity of the IGU, which, together with other factors, determines the ü factor of the door, is more important with respect to thermal performance than which side or sides of which sheet are coated. In addition, although the modalities described here have emissivities of less than or equal to 0.04 for cooling door applications, the use of a high performance gas (such as krypton) may allow an IGU with an emissivity of slightly more than 0.04. , provide the necessary condensation control in some circumstances. In other embodiments, other sealing assemblies may be employed, including, for example, a non-metallic assembly, all of foam, such as the Super Spacer, manufactured by EdgeTech, Inc, which has a heat transfer rate of approximately 2,245 Kcal / hr-m- ° C (1.51 Btu / hr-ft-F). Another suitable sealant assembly is the ThermoPlastic Spacersystem (TPS), manufactured by Lenhardt Maschinenbau GmbH, which has a heat transfer rate of approximately 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). The separation in the modalities described above is 1.27 centimeters (one-half inch). However, although preferred separations vary between 0.793 centimeters (five-sixteenths of an inch) to 1.27 centimeters (one-half inch), other embodiments of the invention may utilize separations of up to 1,905 centimeters (three-quarters of an inch). In addition, although the modalities described above employ 0.317 centimeter (one-eighth inch) thick glass that is tempered (except for the middle sheet), other modalities may use non-tempered glasses or thicknesses that are greater than, or less than 0.317 centimeters (one eighth of an inch). The design parameters of one embodiment of the present invention will be determined, in part, by the application or intended use of the modality. More specifically, the outside ambient temperature, the indoor temperature, and the humidity of the outside environment (and the associated dew point) are important factors in determining the value ü necessary for the design, which in turn determines the design parameters (type of glass, emissivity, number of sheets, gas, etc.). The five columns on the left of Table 3 below provide a list of calculated U values for various applications of the intended use, and include the outside temperature, indoor temperature, outdoor humidity, and dew point calculated for each value or. In addition, the three columns to the right of Table 3 provide an embodiment of the invention that will provide the necessary U value.

TABLE 3 U Values Calculated for Various Environmental Parameters Design Variables of the GUI to Satisfy an Identified U Value Temp. Temp. Value ü Point of Vidri Separation Gas in Exterior Interior Kcal / hr ~ cm2 ° C Dew a hundred o (cm the Degrees C Degrees C (B U / hr-ft2-F (Exterior Moisture (Two (in.)) Cameras (Degrees (Degrees of Relative Glass Sheets F) F) T) Degrees Maximum) C (Degrees F) 26.66 -40 0.927 (0.19) 18.27 60.1 Ti-PS 0.952 axre (80) (-40) (64.9) (3/8) 22.22 -17.77 1.317 (0.27) 14.11 60 CE2 0.793 axre (72) (0) (57.4) (5/16) 26.66 -40 0.732 (0.15) 19.77 66.0 CE2 0.952 krypton (80) (-40) (67.6) (3/8) 26.66 -40 0.878 (0.18) 18.72 61.8 CE2 0.952 argon (80) (-40) (65.7) (3/8) 25.66 -40 1.22 (0.25) 15.72 51.1 CE2 0.952 air (80) (-40) (60.3) (3/8) 26.66 -40 0.780 (0.16) 19.61 65.3 CE2 1.27 krypton (80) (-40) (67.3) (1/2) 26.66 -40 0.829 (0.17) 19.16 63.5 CE2 1.27 argon (80) (-40) (66.5) (1/2) 26.66 -40 0.976 (0.20) 17.83 58.5 CE2 1.27 air (80) (-40) (64.1) (1/2) TABLE 3 (CONTINUED) Values ü Calculated for Various Environmental Parameters Design Variables of the GUI to Satisfy an Identified U Value Temp. Temp. Value U Point of Vidri Separation Gas in Exterior Interior Kcal / hx-cm2oC Dew a hundred o (cm the Degrees C Degrees C (BTO / hr ~ ft2-F (Exterior Moisture (Two (in.)) Cameras (Degrees (Degrees of Relative Glass Sheets F) F) T) Degrees Maximum) C (Degrees F) 26.66 -40 0.683 (0.14) 20.33 68.3 Ti-PS 0.952 argon (80) (-40) (68.6) (3/8) 26.66 -40 0.927 (0.19) 18.33 60.3 Ti-PS 0.952 air (80) (-40) (65.0) (3/8) 26.66 -40 0.585 (0.12) 21.22 72.1 Ti-PS 1.27 krypton (80) (-40) (70.2) (1/2) 26.66 -40 0.634 (0.13) 20.77 70.2 i-PS 1.27 argon (80) (-40) (69.4) (1/2) 26.66 -40 0.829 (0.17) 19.27 64.0 Ti-PS 1.27 air (80) (-40) (66.7) (1/2) 22.22 -23.33 0.878 (0.18) 16.22 68.9 CE2 0.952 argon (72) (-10) (61.2) (3/8) 22.22 -17.77 0.878 (0.18) 34.5 71.1 CE2 0.952 argon (72) (0) (62.1) (3/8) 22.22 -12.22 0.878 (0.18) 17.22 73.4 CE2 0.952 argon (72) (10) (63.0) (3/8) TABLE 3 (CONTINUATION) TJ Values Calculated for Several Reliable Environmental Design Parameters of the GUI to Satisfy an Identified TJ Value Temp. Temp. Value U Point of Vidri Separation Gas in Exterior Interior Kcal / hr-cm2 ° C Dew a hundred o (cm the Degrees C Degrees C (BTU / hr-ft2 ~ F (Exterior Moisture (Two (in.)) Cameras (Degrees (Degrees of Relative Glass Sheets F) F) T) Degrees Maximum) C (Degrees F) 26.66 -17.77 0.878 (0.18) 20.66 69.7 CE2 0.952 argon (80) (0) (69.2) (3/8) 32.22 -17.77 0.878 (0.18) 46.1 68.3 CE2 0.952 argon (90) (0) (78.1) (3/8) 21.11 -28.88 1024 (0.21) 13.05 60.1 CE2 0.952 air (70) (-20) (55.5) (3/8) 30 -12.22 0.536 (0.11) 25.27 75.9 Ti-PS 0.952 krypton (86) (-22) (77.5) (3/8) 26.66 -40 0.927 (0.19) 18.33 60.3 CE2 1.27 air (80) (-40) (65.0) (1/2) 21.11 0 0.878 (0.18) 17.44 79.6 CE2 0.952 argon (70) (32) (63.4) (3/8) 26.66 0 0.878 (0.18) 22.33 77.2 CE2 0.952 argon (80) (32) (72.2) (3/8) The design parameters in Table 3 identify the type of glass (which is 0.317 centimeters (one eighth of an inch) thick), the separation between the sheets, and the gas in the chambers. In addition, all IGUs in Table 3 include a third sheet of uncoated glass that is 0.317 centimeters (one-eighth of an inch) thick, and that is placed between the two glass sheets identified in the table. CE1 in Table 3 refers to Comfort El, which has an emissivity of 0.35 and is sold by AEG Industries, Inc. The foregoing has described the principles, embodiments and modes of operation of the present invention. However, the invention should not be considered as being limited to the particular embodiments described above, but should be considered as being illustrative and not restrictive. It will be appreciated that variations can be made in those modalities by those with experience in the art, without departing from the scope of the present invention. Although the application of the present invention has been described in the application of a refrigerator or freezer door, other applications may include vending machines, skylights or refrigerated trucks. In some of these applications, the condensation on the second side or the colder side of the glass, may not be a problem because the glass is not in the door that opens periodically, exposing the cold glass to a more humid environment. As a result, the key factors in glass design are economical (ie, energy costs and the cost of glass and its installation), visible transmittance, durability, and other considerations. Although a preferred embodiment of the present invention has been described above, it should be understood that it has been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by the exemplary embodiment described above. Obviously, numerous modifications and variations of the present invention are possible, in light of the above teachings. Therefore, it should be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described herein.

Claims

CLAIMS 1. A door for cooling adapted to be mounted in a refrigerant compartment, the door comprises: an inner glass sheet including a first surface and a second surface, the first surface of the inner sheet being positioned adjacent the interior of the refrigerant compartment; an external glass sheet that includes a first surface and a second surface, the first surface of the outer sheet is positioned adjacent to the outer environment of the cooling compartment; a half glass sheet placed between the inner and outer glass sheets; a first sealant assembly mounted around the periphery of the inner glass sheet and the middle glass sheet, to maintain the inner sheet and the middle sheet in a spaced apart relationship; a second sealing assembly positioned around the periphery of the middle glass sheet and the outer glass sheet, to maintain the middle sheet and the outer sheet in a spaced relation to one another; a first coating of low emissivity adjacent to the second surface of the inner glass sheet; a second coating of adjacent low emissivity of the second surface of the outer glass sheet; the inner sheet, the outer sheet, the middle sheet, the first sealing assembly, the second sealing assembly, and the first and second low emissivity coatings form an insulating glass unit having a U value substantially equal to, or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F) substantially preventing the formation of condensation on the first surface of the outer glass sheet, without the application of electricity to heat the first surface of the outer glass sheet; and a frame secured around the periphery of the insulating glass unit. The door for cooling according to claim 1, characterized in that it further comprises: a first chamber defined by the inner glass sheet, the middle glass sheet, and the first sealing assembly; a second chamber defined by the middle glass sheet, the outer glass sheet, and the second sealing assembly; and a gas placed in the first and second chambers. The door for cooling according to claim 2, characterized in that: the inner, middle and outer glass sheets have a thickness substantially equal to 0.317 centimeters (one eighth of an inch); the inner and middle glass sheets are separated by a distance substantially equal to 1.27 centimeters (one half inch); and the middle and outer glass sheets are spaced a distance substantially equal to 1.27 centimeters (one half inch). 4. The door for cooling according to claim 2, characterized in that at least one sheet of glass is formed of Comfort Ti-PS. The door for cooling according to claim 2, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). The door for cooling according to claim 5, characterized in that: the inner, middle and outer glass sheets have a thickness substantially equal to 0.317 centimeters (one eighth of an inch); the inner and middle glass sheets are separated by a distance substantially equal to 1.27 centimeters (one half inch); and the middle and outer glass sheets are spaced a distance substantially equal to 1.27 centimeters (one half inch). The door for cooling according to claim 2, characterized in that the gas of the first chamber and the second chamber is the same. The door for cooling according to claim 2, characterized in that the gas of the first chamber and the second chamber is not the same. 9. The door for cooling according to claim 2, characterized in that the gas is selected from the group consisting of argon, krypton and air. The door for cooling according to claim 1, characterized in that the insulating glass unit has a U value substantially equal to or less than 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F). The door for cooling according to claim 1, characterized in that the outer sheet and the inner sheet have an emissivity substantially equal to, or less than 0.05. The door for cooling according to claim 1, characterized in that the outer sheet and the inner sheet have an emissivity substantially equal to, or less than 0.03. The door for cooling according to claim 1, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.04. The door for cooling according to claim 1, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 15. The door for cooling according to claim 1, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.0025. 16. The door for refligeration according to claim 2, characterized in that the first and second coatings of low emissivity are selected from the group consisting of a silver oxide with a titania base and adulterated with fluorine. 17. The door for cooling according to claim 2, characterized in that the first and second coatings of low emissivity are applied with a process selected from the group consisting of sputter coating, pyrolytic coating and spray coating. 18. The door for cooling according to claim 2, characterized in that the frame is formed of a material selected from the group consisting of extruded plastic, aluminum and fiberglass. 19. The door for refrigeration according to claim 1, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 28.88 degrees centigrade (minus 20 degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 21.11 degrees Celsius (seventy degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. The door for cooling according to claim 1, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 40 degrees centigrade (minus forty degrees Fahrenheit); the temperature of the external medium is substantially equal to or greater than 25.66 degrees Celsius (eighty degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. The door for cooling according to claim 1, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 17.77 degrees centigrade (zero degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 22.22 degrees Celsius (seventy-two degrees Fahrenheit); and the humidity in the environment is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. 22. The door for cooling according to claim 2, characterized in that at least one sheet of glass is formed of Comfort E2. The door for cooling according to claim 1, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). 24. The door for cooling according to claim 1, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer velocity substantially equal to or less than 2.245 Kcal / hr-m- ° C (1.51 Btu / hr-ft-F). 25. The door for cooling according to claim 1, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 1.249 Kcal / hr-m- ° C (0.84 Btu / hr-ft-F). 26. A door for cooling adapted to be mounted in a refrigerant compartment, the door comprising: an inner glass sheet including a first surface and a second surface, the first surface of the inner sheet being positioned adjacent to the interior of the refrigerant compartment; an external glass sheet that includes a first surface and a second surface, the first surface of the outer sheet is positioned adjacent to the outer environment of the cooling compartment; a half glass sheet placed between the inner and outer glass sheets; a first sealant assembly mounted around the periphery of the inner glass sheet and the middle glass sheet, to maintain the inner sheet and the middle sheet in a spaced apart relationship; a second sealing assembly positioned around the periphery of the middle glass sheet and the outer glass sheet, to maintain the middle sheet and the outer sheet in a spaced relation to one another; a first coating of low emissivity adjacent to the second surface of the inner glass sheet; a second coating of adjacent low emissivity of the second surface of the outer glass sheet; the inner sheet, the outer sheet, the middle sheet, the first sealing assembly, the second sealing assembly, and the first and second low emissivity coatings form an insulating glass unit having a U value substantially equal to, or less than 0.04 substantially avoiding the formation of condensation on the first surface of the outer glass sheet, without the application of electricity to heat the first surface of the outer glass sheet; and a frame secured ad the periphery of the insulating glass unit. The door for cooling according to claim 26, characterized in that it further comprises: a first chamber defined by the inner glass sheet, the middle glass sheet, and the first sealing assembly; a second chamber defined by the middle glass sheet, the outer glass sheet, and the second sealing assembly; and a gas placed in the first and second chambers. 28. The door for cooling according to claim 27, characterized in that: the inner, middle and outer glass sheets have a thickness substantially equal to 0.317 centimeters (one eighth of an inch); the inner and middle glass sheets are separated by a distance substantially equal to 1.27 centimeters (one half inch); and the middle and outer glass sheets are spaced a distance substantially equal to 1.27 centimeters (one half inch). 29. The door for cooling according to claim 27, characterized in that at least one sheet of glass is formed of Comfort Ti-PS. 30. The door for cooling according to claim 27 ,. characterized in that the gas is selected from the g consisting of argon, krypton and air. 31. The door for cooling according to claim 26, characterized in that the insulating glass unit has a value ü substantially equal to or less than 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F). 32. The door for cooling according to claim 26, characterized in that the outer sheet and the inner sheet have an emissivity substantially equal to, or less than 0.05. 33. The door for cooling according to claim 26, characterized in that the outer sheet and the inner sheet have an emissivity substantially equal to, or less than 0.03. 34. The door for cooling according to claim 26, characterized in that the insulating glass unit has a U value substantially equal to, or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F). 35. The door for cooling according to claim 26, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 36. The door for cooling according to claim 26, characterized in that the insulating glass unit has an emissivity substantially equal to or less than 0.0025. 37. The door for refrigeration according to claim 27, characterized in that the low emissivity coatings are selected from the g consisting of a silver oxide with a titania base and adulterated with fluorine. 38. The door for cooling according to claim 27, characterized in that the first and second coatings of low emissivity are applied with a process selected from the g consisting of sputter coating, pyrolytic coating and spray coating. 39. The door for cooling according to claim 27, characterized in that the frame is formed of a material selected from the g consisting of extruded plastic, aluminum and fiberglass. 40. The door for cooling according to claim 26, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 28.88 degrees centigrade (minus 20 degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 21.11 degrees Celsius (seventy degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. 41. The door for refrigeration according to claim 26, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 40 degrees centigrade (minus forty degrees Fahrenheit); the temperature of the outside medium is substantially equal to, or greater than 26.66 degrees Celsius (eighty degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. 42. The door for cooling according to claim 26, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 17.77 degrees centigrade (zero degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 22.22 degrees Celsius (seventy-two degrees Fahrenheit); and the humidity in the environment is substantially equal to, or greater than sixty percent; and wherein the first surface of the outer glass sheet is substantially free of condensation. 43. The door for cooling according to claim 27, characterized in that at least one sheet of glass is formed of Comfort E2. 44. The door for cooling according to claim 26, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). 45. The door for cooling according to claim 26, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to, or less than 2.245 Kcal / hr-m- ° C (1.51 Btu / hr-ft-F). 46. The door for cooling according to claim 26, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 1,249 cal / hr-m- ° C (0.84 Btu / hr-ft-F). 47. A door for cooling having an external surface and adapted to be mounted in a refrigerant compartment, the door comprising: a first sheet of glass; a second sheet of glass; a first sealing assembly positioned around the periphery of the first glass sheet and the second glass sheet to hold the first sheet and the second sheet in a spaced relation to one another; a first coating of low emissivity adjacent to a surface of the first sheet or the second sheet of glass; the first sheet and the second glass sheets, the first sealing assembly, and the first low emissivity coating form an insulating glass unit having a value ü substantially equal to, or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F); and a frame secured around the periphery of the insulating glass unit. 48. The refrigerator door according to claim 47, characterized in that it further comprises: a third sheet of glass; a second sealing assembly positioned around the periphery of the second glass sheet and the third glass sheet, to hold the second sheet and the third sheet in a spaced apart relationship; and wherein the insulating glass unit further includes the third glass sheet and the second sealing assembly. 49. The door for cooling according to claim 48, characterized in that it also includes a second coating of low emissivity adjacent to a surface of the first sheet, the second sheet or the third sheet of glass. 50. The door for cooling according to claim 49, characterized in that the U value of the insulating glass unit is effective to substantially prevent the formation of condensation on the outer surface of the door, without the application of electricity to heat the surface external, when the interior temperature of the refrigerant compartment is substantially equal to, or less than -17.77 degrees centigrade (zero degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 22.22 degrees Celsius (seventy-two degrees Fahrenheit); and the humidity in the environment is substantially equal to, or greater than sixty percent. 51. The refrigerator door according to claim 47, characterized in that the U value of the insulating glass unit is effective to substantially prevent the formation of condensation on the external surface of the door, without the application of electricity to heat the surface external, when the interior temperature of the refrigerant compartment is substantially equal to, or less than -17.77 degrees centigrade (zero degrees Fahrenheit); The temperature of the outside medium is substantially equal to, or greater than, 22. 22 degrees Celsius (seventy-two degrees Fahrenheit); and the humidity in the environment is substantially equal to, or greater than sixty percent. 52. The door for cooling according to claim 51, characterized in that it further comprises: a first chamber defined by the first glass sheet, the second glass sheet, and the first sealing assembly; and a gas placed in the first chamber. 53. The door for cooling according to claim 52, characterized in that the first sealing assembly has a heat transfer rate substantially equal to, or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft- F). 54. The door for cooling according to claim 43, characterized in that the gas is selected from the group consisting of argon, krypton and air. 55. The door for cooling according to claim 47, characterized in that the insulating glass unit has a U value substantially equal to or less than 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F). 56. The door for cooling according to claim 47, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.04. 5 . The door for cooling according to claim 47, characterized in that the insulating glass unit has an emissivity substantially equal to or less than 0.01. 58. The door for cooling according to claim 47, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.0025. 59. The door for cooling according to claim 47, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 28.88 degrees centigrade (minus 20 degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 21.11 degrees Celsius (seventy degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the external surface of the door is substantially free of condensation. 60. The door for cooling according to claim 47, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 40 degrees centigrade (minus forty degrees Fahrenheit); the temperature of the outside medium is substantially equal to, or greater than 26.66 degrees Celsius (eighty degrees Fahrenheit); and the humidity in the external medium is substantially equal to, or greater than sixty percent; and wherein the external surface of the door is substantially free of condensation. 61. A door for cooling having an exterior surface and adapted to be mounted in a refrigerant compartment, the door comprising: a first sheet of glass; a second sheet of glass; a first sealing assembly positioned around the periphery of the first glass sheet and the second glass sheet to hold the first sheet and the second sheet in a spaced relation to one another; a first coating of low emissivity adjacent to a surface of the first sheet or the second sheet of glass; the first sheet and the second glass sheet, the first sealing assembly, and the first low emissivity coating form an insulating glass unit having an emissivity substantially equal to, or less than 0.04, substantially preventing the formation of condensation on the outer surface of the door for cooling, without the application of electricity to heat the external surface; and a frame secured around the periphery of the insulating glass unit. 62. The refrigerator door according to claim 61, characterized in that it further comprises: a third sheet of glass; a second sealant assembly positioned around the periphery of the second glass sheet and the third glass sheet to hold the second sheet and the third sheet in a spaced relation to one another; and wherein the insulating glass unit further includes the third glass sheet and the second sealing assembly. 63. The door for cooling according to claim 62, characterized in that it also includes a second coating of low emissivity adjacent to a surface of the first sheet, the second sheet or the third sheet of glass. 64. The door for cooling according to claim 61, characterized in that it further comprises: a first chamber defined by the first glass sheet, the second glass sheet, and the first sealing assembly; and a gas placed in the first chamber. 65. The door for cooling according to claim 64, characterized in that the first sealing assembly has a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft- F). 66. The door for cooling according to claim 65, characterized in that the gas is selected from the group consisting of argon, krypton and air. 67. The door for cooling according to claim 61, characterized in that the insulating glass unit has a U value substantially equal to or less than 0.780 Kcal / hr-m2oC (0.16 BTU / hr-sq ft-F). 68. The door for cooling according to claim 61, characterized in that the insulating glass unit has a U value substantially equal to, or less than 0.297 Kcal / hr-m- ° C (0.20 BTU / hr-sq ft-F) ). 69. The door for cooling according to claim 61, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 70. The door for cooling according to claim 61, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.0025. 71. A method for manufacturing a component of a door for cooling, having an external surface, the method comprises the steps of: providing a first sheet of glass; provide a second sheet of glass; providing a first coating of low emissivity adjacent a surface of the first sheet of glass or the second sheet of glass; placing a first sealing assembly around the periphery of the first sheet of glass and the second sheet of glass to hold the first sheet and the second sheet in a spaced relationship from one another; and the first sheet of glass, the second sheet of glass, and the first seal assembly form an insulating glass unit having a U value substantially equal to, or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft. -F), which substantially prevents the formation of condensation on the external surface of the component of the door for cooling, without the application of electricity to heat the component of the door. 72. The method according to claim 71, characterized in that the first glass sheet, the second glass sheet, and the first sealing assembly define a first chamber; and which further comprises the step of placing a gas in the first chamber. 73. The method according to claim 71, characterized in that it further comprises the steps of: providing a third sheet of glass; placing a second seal assembly positioned around the periphery of the second sheet of glass and the third sheet of glass to hold the second sheet and the third sheet in a spaced relation to one another; and wherein the insulating glass unit further includes the third glass sheet and the second sealing assembly. 74. The method according to claim 73, characterized in that the third glass sheet includes a coating of low emissivity adjacent to a surface of the third glass sheet. 75. The method according to claim 71, characterized in that the first glass sheet is formed of Comfort Ti-PS. 76. The method according to claim 71, characterized in that the first sealing assembly has a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). . 77. The method according to claim 76, characterized in that: the first and second glass sheets have a thickness substantially equal to 0.317 centimeters (one eighth of an inch); and the first and second glass sheets are spaced a distance substantially equal to 1.27 centimeters (one half inch). 78. The method according to claim 71, further characterized in that it includes the step of placing the insulating glass unit in a door frame. 79. The method according to claim 72, characterized in that the gas is selected from the group consisting of argon, krypton and air. 80. The method according to claim 71, characterized in that the insulating glass unit has a value ü substantially equal to or less than 0.780 Kcal / hr-m2 ° C (0.16 BTU / hr-sq ft-F). 81. The method according to claim 71, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.04. 82. The method according to claim 71, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 83. The method according to claim 71, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.0025. 84. The method according to claim 71, characterized in that the low emissivity coating is selected from the group consisting of a silver oxide with titania base and fluorinated adulterated. 85. The method according to claim 71, characterized in that the low emissivity coating is applied with a process selected from the group consisting of sputter coating., pyrolytic coating and spray coating. 86. The method according to claim 72, characterized in that the first glass sheet is formed of Comfort E2. 87. The door for cooling according to claim 73, characterized in that the first and second sealing assemblies have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr- ft-F). 88. The door for cooling according to claim 71, characterized in that the first sealing assembly has a heat transfer rate substantially equal to, or less than 2.245 Kcal / hr-m- ° C (1.51 Btu / hr-ft- F). 89. The door for cooling according to claim 71, characterized in that the first sealing assembly has a heat transfer rate substantially equal to or less than 1,249 Kcal / hr-m- ° C (0.84 Btu / hr-ft- F). 90. A method for manufacturing a component of a door for refrigeration, having an external surface, the method comprises the steps of: providing a first sheet of glass; provide a second sheet of glass; providing a first coating of low emissivity adjacent a surface of the first sheet of glass or the second sheet of glass; placing a first sealing assembly around the periphery of the first sheet of glass and the second sheet of glass to hold the first sheet and the second sheet in a spaced relationship from one another; and the first glass sheet, the second glass sheet, and the first sealing assembly form an insulating glass unit having an emissivity substantially equal to, or less than 0.04, which substantially prevents the formation of condensation on the external surface of the component of the door for cooling, without the application of electricity to heat the component of the door. 91. The method according to claim 90, characterized in that the first glass sheet, the second glass sheet, and the first sealing assembly define a first chamber; and further comprising the step of placing a gas in the first chamber. 92. The method according to claim 90, characterized in that it further comprises the steps of: providing a third sheet of glass; placing a second seal assembly positioned around the periphery of the second sheet of glass and the third sheet of glass to hold the second sheet and the third sheet in a spaced relation to one another; and wherein the insulating glass unit further includes the third glass sheet and the second sealing assembly. 93. The method according to claim 92, characterized in that the third glass sheet includes a coating of low emissivity adjacent to a surface of the third glass sheet. 94. The method according to claim 90, characterized in that the first sealing assembly has a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). . 95. The method according to claim 90, characterized in that it further comprises the step of placing the insulating glass unit in a door frame. 96. The method according to claim 91, characterized in that it further comprises the step of placing the insulating glass unit in a door frame. 97. The method according to claim 96, characterized in that the gas is selected from the group consisting of argon, krypton and air. 98. The method according to claim 90, characterized in that the insulating glass unit has a U value substantially equal to or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr-sq ft-F). 99. The method according to claim 90, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 100. The method according to claim 90, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.0025. 101. The door for cooling according to claim 92, characterized in that the first and second sealing assemblies have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft- F). 102. The door for cooling according to claim 90, characterized in that the first sealing assembly has a heat transfer rate substantially equal to, or less than 2.245 Kcal / hr-m- ° C (1.51 Btu / hr-ft-). F). 103. The door for cooling according to claim 90, characterized in that the first sealing assembly has a heat transfer rate substantially equal to, or less than 1249 cal / hr-m- ° C (0.84 Btu / hr-ft- F). 104. A substantially transparent insulating glass unit having an external surface and for use with a cooling compartment that resides in an outdoor environment and has an interior cooling compartment; the door of the insulating glass unit comprises: a first sheet of glass; a second sheet of glass; a first sealing assembly positioned around the periphery of the first glass sheet and the second glass sheet to hold the first sheet and the second sheet in a spaced relation to one another; a first low emissivity coating adjacent a surface of the first sheet or the second sheet of glass, and the first sheet of glass, the second sheet of glass, and the first seal assembly provide the insulating glass unit with an effective U value to substantially prevent the formation of condensation on the external surface, without the acation of electricity to heat the external surface of the insulating glass unit, when the internal temperature of the refrigerant compartment is substantially equal to, or less than minus 17.77 degrees centigrade (zero Fahrenheit degrees); the temperature of the outside medium is substantially equal to, or greater than, 21.11 degrees Celsius (seventy degrees Fahrenheit); and the humidity in the external environment is substantially equal to, or greater than sixty percent. 105. The door according to claim 104, characterized in that it further comprises: a third sheet of glass; and a second sealant assembly positioned around the periphery of the second glass sheet and the third glass sheet to hold the first sheet and the second sheet in a spaced apart relationship. 106. The door according to claim 105, characterized in that it further includes a second coating of low emissivity adjacent to a surface of the first sheet, the second sheet or the third sheet of glass. 107. The door according to claim 106, characterized in that the insulating glass unit has a value ü which substantially prevents the formation of condensation on the external surface, when the internal temperature of the cooling compartment is substantially equal to, or less than less 40 degrees Celsius (minus forty degrees Fahrenheit); the temperature of the outside medium is substantially equal to, or greater than 26.66 degrees Celsius (eighty degrees Fahrenheit); and the humidity in the external environment is substantially equal to, or greater than sixty percent. 108. The door according to claim 106, characterized in that the low emissivity coating is effective to make the insulating glass unit have a U value substantially equal to, or less than 0.976 kcal / hr-m2oC (0.2 BTU / hr) -sq ft-F). 109. The door for cooling according to claim 105, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). 110. The door for cooling according to claim 104, characterized in that the insulating glass unit has a U value substantially equal to, or less than 0.780 cal / hr-m2oC (0.16 BTU / hr-sq ft-F). 111. The door for refligeration according to claim 104, characterized in that the first sheet or the second sheet have an emissivity substantially equal to, or less than 0.05. 112. The door for cooling according to claim 104, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.04. 113. The door for cooling according to claim 104, characterized in that the insulating glass unit has an emissivity substantially equal to, or less than 0.01. 114. The door for refrigeration according to claim 104, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 28.88 degrees centigrade (minus 20 degrees Fahrenheit); the temperature of the outside medium is substantially equal to or greater than 21.11 degrees Celsius (seventy degrees Fahrenheit); and the humidity in the external environment is substantially equal to, or greater than sixty percent. 115. The door for cooling according to claim 104, characterized in that the interior temperature of the refrigerant compartment is substantially equal to, or less than minus 40 degrees centigrade (minus forty degrees Fahrenheit); the temperature of the external medium is substantially equal to, or greater than 26.66 degrees Celsius (eighty degrees Fahrenheit) / and the humidity in the external environment is substantially equal to, or greater than sixty percent. 116. The door for refligeration according to claim 105, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- °. C (1.73 Btu / hr-ft-F). 117. A unit for refrigeration including an insulated enclosure defining a compartment, a cooling system, and a door adapted to be mounted in a compartment opening, the door has an external surface and comprises: a first sheet of glass; a second sheet of glass; a first sealing assembly positioned around the periphery of the first glass sheet and the second glass sheet to hold the first sheet and the second sheet in a spaced relation to one another; a first low emissivity coating adjacent a surface of the first or second glass sheet; the first sheet, the second sheet, the first sealing assembly, and the first low emissivity coating form an insulating glass unit having a value ü substantially equal to, or less than 0.976 Kcal / hr-m2oC (0.2? G? / hr-sq ft-F), which substantially prevents the formation of condensation on the external surface of the door without the application of electricity to heat the first surface; and a frame secured around the periphery of the insulating glass unit. 118. The door according to claim 117, characterized in that it further comprises: a third sheet of glass; and a second sealing assembly positioned around the periphery of the second glass sheet and the third glass sheet to hold the second sheet and the third sheet in a spaced relation to one another. 119. The door for cooling according to claim 117, characterized in that it further comprises: a first chamber defined by the first glass sheet, the second glass sheet, and the first sealing assembly; a second chamber defined by the middle glass sheet, the outer glass sheet, and the second sealing assembly; and a gas placed in the first and second chambers. 120. The door for cooling according to claim 118, characterized in that the first sealing assembly and the second sealing assembly each have a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft-F). 121. The door for cooling according to claim 117, characterized in that the door for cooling has an emissivity substantially equal to, or less than 0.04. 122. The door for cooling according to claim 117, characterized in that the door for cooling has an emissivity substantially equal to, or less than 0.01. 123. The door for cooling according to claim 117, characterized in that the first sealing assembly has a heat transfer rate substantially equal to or less than 2,572 Kcal / hr-m- ° C (1.73 Btu / hr-ft- F). external (60), so that the glass door (10), as a whole, has a U-value that prevents the formation of condensation on the external surface of the outer leaf (60) of the glass door, without the application of electricity to heat the door, while also providing the desired evaporation rate of condensation on the inner side of the inner sheet (70) of the glass door.